1. Field of the Invention
The present invention relates to motion picture developing machines and, more particularly, to the field of the several friction drive systems at present used and which are commonly referred to, in the prior art as, "bottom-drive", "weighted bottom-drive", "tendency drive", and "demand drive".
2. Description of the Prior Art
The driving mechanism for propelling film through the various treating baths which are used in motion picture developing machines is typically a sprocket and tooth arrangement; the teeth engaging the film perforations, or a friction drive arrangement relying upon the adhesion between the film and the driving rollers.
These known friction driving systems for motion picture film developing machines are affected by various practical and functional drawbacks, above all with respect to the coupling of the film supporting rollers with the driving rollers, said rollers being the essential driving components of all the prior art developing machines. The operation of these conventional prior art machines does not entail specific drawbacks as long as the velocity of the film is kept moderately low. On the contrary, because of the reliance upon friction to drive these prior art devices, serious problems occur whenever the film velocity exceeds certain limits.